Semiconductor switching module and method

ABSTRACT

The invention relates to a semiconductor switching module for on-board electrical supply systems comprising a plurality of semiconductor chips, and a method for producing the same. The semiconductor switching module has at least one half-bridge circuit comprising a first semiconductor circuit chip as LSS (low side switch) and a second semiconductor circuit chip as HSS (high side switch) on a common circuit structure. The circuit structure includes contact pads on the top side of the circuit structure and lead connections with external contact areas on the underside of the circuit structure and with internal contact areas on the top side of the circuit structure. In this case, at least one of the semiconductor circuit chips is arranged on contact pads of the circuit structure using flip-chip technology and is electrically and cohesively connected to the contact pads by using diffusion solder layers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Utility Patent Application claims priority to German ApplicationNo. DE 10 2006 037 118.6, filed Aug. 7, 2006, which is hereinincorporated by reference.

BACKGROUND

The invention relates to a semiconductor switching module for on-boardelectrical supply systems, including a plurality of semiconductor chips.The invention furthermore relates to a method for producing asemiconductor switching module of this type. The semiconductor switchingmodule is intended to realize at least one half-bridge circuit includinga first semiconductor circuit chip as LSS (low side switch) and a secondsemiconductor circuit chip as HSS (high side switch) on a common circuitstructure. For this purpose, the circuit structure has lead connectionswith external contact areas on the underside of the circuit structureand internal contact areas on the top side of the circuit structure andalso with contact pads on the top side of the circuit structure.

A semiconductor switching module forms a multi-chip module for “motorbridges.” MCM modules of this type are based on a DCB technique (directcopper bonding), in which a plurality of semiconductor circuit chips arepaste-soldered alongside one another and contact-connected by usingbonding wires. A paste solder bonding process of this type can only beused if the semiconductor circuit chips are arranged in “drain-downmounting” on a circuit structure. In the case of this “drain-downmounting”, with the aid of the paste solder, a large-area externalcontact of the semiconductor circuit chip, which covers the entire rearside of the semiconductor circuit chip, is electrically connected to acorrespondingly large contact pad of the circuit structure.

If the semiconductor circuit chip has a plurality of small-areaelectrodes, too, which are intended to be arranged on a correspondingcontact pad of the circuit structure by using surface mounting, as isnecessary in the case of a flip-chip technology, then the paste solderbonding process fails since short-circuits can occur between thesmall-area and large-area electrodes of the semiconductor circuit chipthat are surface-mounted alongside one another.

Consequently, the reliability of multi-chip modules produced by thepaste-solder bonding process is manifested only if the semiconductorcircuit chips are mounted by their large-area drain electrodes onindividual contact pads that are insulated from one another.Consequently, nodes of a half-bridge circuit have to be produced byusing correspondingly thick bonding tape and/or bonding wireconnections.

For these and other reasons there is a need for the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the present invention and are incorporated in andconstitute a part of this specification. The drawings illustrate theembodiments of the present invention and together with the descriptionserve to explain the principles of the invention. Other embodiments ofthe present invention and many of the intended advantages of the presentinvention will be readily appreciated as they become better understoodby reference to the following detailed description. The elements of thedrawings are not necessarily to scale relative to each other. Likereference numerals designate corresponding similar parts.

The invention will now be explained in more detail with reference to theaccompanying figures.

FIG. 1 illustrates a schematic cross section through a semiconductorswitching module of one embodiment of the invention.

FIG. 2 illustrates a schematic plan view of a circuit structure for asemiconductor switching module in accordance with FIG. 1.

FIG. 3 illustrates a schematic circuit diagram of a half-bridge circuitfor an on-board electrical supply system.

FIG. 4 illustrates a schematic plan view of an equipped circuit carrier.

DETAILED DESCRIPTION

In the following Detailed Description, reference is made to theaccompanying drawings, which form a part hereof, and in which is shownby way of illustration specific embodiments in which the invention maybe practiced. In this regard, directional terminology, such as “top,”“bottom,” “front,” “back,” “leading,” “trailing,” etc., is used withreference to the orientation of the Figure(s) being described. Becausecomponents of embodiments of the present invention can be positioned ina number of different orientations, the directional terminology is usedfor purposes of illustration and is in no way limiting. It is to beunderstood that other embodiments may be utilized and structural orlogical changes may be made without departing from the scope of thepresent invention. The following detailed description, therefore, is notto be taken in a limiting sense, and the scope of the present inventionis defined by the appended claims.

One embodiment optimizes a semiconductor switching module for a “motorbridges” application and ensures the reliability of a motor bridgecircuit of this type. The circuit structure is simplified and the numberof bonding connections carrying high current are minimized.

One embodiment provides a semiconductor switching module for on-boardelectrical supply systems including a plurality of semiconductor chips,and a method for producing the same. The semiconductor switching modulehas at least one half-bridge circuit including a first semiconductorcircuit chip as LSS (low side switch) and a second semiconductor circuitchip as HSS (high side switch) on a common circuit structure. Thecircuit structure includes contact pads on the top side of the circuitstructure and lead connections with external contact areas on theunderside of the circuit structure and with internal contact areas onthe top side of the circuit structure. In this case, at least one of thesemiconductor circuit chips is arranged on contact pads of the circuitstructure using flip-chip technology and is electrically and cohesivelyconnected to the contact pads by using diffusion solder layers.

A semiconductor switching module of this type allows for large-area rearside contacts of the semiconductor circuit chips to be electricallyconnected and fixed on separate connection contact areas of a circuitcarrier, and it is also possible to connect nodes of a half-bridge orbridge circuit by using a common large-area contact pad of a circuitcarrier by virtue of the fact that it is possible to interconnect alarge-area drain electrode of a first semiconductor power chip usingdrain-down technology on a common contact pad with a large-area sourceelectrode of a semiconductor circuit chip using flip-chip technology.

In this case, the large-area contact pad can be realized by acorrespondingly thick metal plate, such that high switching currents canpass through the node without corresponding bonding connections havingto be established. The diffusion solder layers simultaneously ensurethat a small-area gate electrode of the second semiconductor circuitchip arranged using flip-chip technology can be connected on asmall-area contact pad of the circuit carrier, which contact pad isinsulated and electrically isolated from the large-area contact pad, byusing the one diffusion solder layer, without the risk of short-circuitsbetween the small-area electrode and the large-area electrode of thesecond semiconductor circuit chip arranged using flip-chip technologyoccurring as a result of the connecting technique. Consequently, areliable semiconductor switching module is realized in the form of ahalf-bridge circuit for motor driving arrangements in on-boardelectrical supply systems.

In one embodiment, the first and the second semiconductor circuit chipare power semiconductor components of the MOSFET type. The powersemiconductor components have, on their rear sides, large-areasurface-mountable drain electrodes and, on their top sides,surface-mountable electrodes including a large-area source electrode anda small-area gate electrode. In this embodiment, large-area isunderstood to mean an electrode which covers virtually the entire topside or rear side of a semiconductor circuit chip. By contrast,small-area is understood to mean an electrode which takes up only asmall region of the top side or rear side of a power semiconductor chip,such as, for example, a control or gate electrode of a powersemiconductor component.

For realizing a half-bridge circuit, the circuit structure of thesemiconductor switching module has at least two contact pads, wherein alarge-area contact pad receives a drain electrode of the firstsemiconductor circuit chip and a source electrode of the secondsemiconductor circuit chip and electrically connects them to form anode, and wherein a small-area contact pad is electrically connected toa gate electrode of the second semiconductor circuit chip and isdistinctly insulated from the first large-area contact pad of thecircuit structure. In one embodiment, the individual electrodes of thesemiconductor circuit chips are diffusion-soldered on the contact padsof the circuit structure and it is thereby ensured that no inadvertentshort-circuits that jeopardize the reliability of the semiconductormodule arise during flip-chip mounting.

In this embodiment, the first semiconductor circuit chip issurface-mounted by its large-area drain electrode on its rear side, byusing a diffusion solder layer, with a large-area contact pad of thecircuit structure using DCB (direct copper bonding). At the same time,the contact pad is connected to the large-area source electrode of thetop side of the second semiconductor circuit chip mounted usingflip-chip technology in such a way that the large-area contact pad formsthe node of the half-bridge circuit.

The diffusion solder layers are composed of a diffusion solder materialhaving at least one of the materials AuSn, AgSn, CuSn and/or InAg. Oneadvantage of such diffusion solder layers, besides precise separation ofthe electrode regions to be connected during flip-chip mounting, is, inaddition, that the intermetallic phases of the diffusion soldermaterials that arise have a higher melting point than the diffusionsolder temperatures required for forming the diffusion solder layer.

In a further embodiment of the invention, the semiconductor module hasat least five lead connections. Lead connections of this type have anexternal contact area on the underside of the circuit structure, whichis externally accessible, and an internal contact area on the top sideof the circuit structure, which internal contact area can be connectedto electrodes of the circuit chips by using bonding connections.

A first lead connection is connected to ground potential by its externalcontact area and is connected by its internal contact area, by using abonding tape connection or by using aluminum bonding wires, to thesource electrode of the first semiconductor circuit chip. Since, byusing the bonding tape connection or by using the aluminum bondingwires, high current density is to be transported from the sourceelectrode of the first semiconductor circuit chip to the groundpotential of the lead connection, a high cross section is provided bothfor the bonding tape connection and for the aluminum bonding wires,which cross section ensures that there is no risk of such a connectionmelting.

A second lead connection enables, via its external contact area anaccess to a gate electrode of the first semiconductor circuit chip. Forthis purpose, the internal contact area of the second lead connection isconnected to the gate electrode of the first semiconductor circuit chipby using a bonding wire. Since only signal currents flow via such abonding wire, the bonding wire can be realized from a gold wire having athickness of a few micrometers. Such thin bonding wire connectionsrequire relatively small-area contact pads on the circuit structure andcorrespondingly small-area contact areas on the semiconductor circuitchips to be used.

A third lead connection enables, by its external contact area an accessto a node of the semiconductor switching module. For this purpose, theinternal contact area of the third lead connection is connected to acommon contact pad of the circuit structure by using a bonding tapeconnection or by using aluminum bonding wires. Since the common contactpad of the circuit structure simultaneously represents the node of thehalf-bridge circuit, access to the node of the semiconductor switchingmodule is thus assured via the third lead connection and via itsexternal contact area.

A fourth lead connection enables, via its external contact area anaccess to a gate electrode of the second semiconductor circuit chip. Forthis purpose, the internal contact area of the fourth lead connection isconnected to a small-area contact pad of the circuit structure by usinga bonding wire. The gate electrode of the second semiconductor circuitchip is fixed on the small-area contact pad by using a diffusion solderlayer using flip-chip technology. With this fourth lead connection, notonly is access to a gate electrode made possible, but advantages of aflip-chip construction for the second semiconductor circuit chip alsobecome clear.

A fifth lead connection is connected to a supply potential by itsexternal contact area. The lead connection is connected by its internalcontact area, by using bonding tapes or by using aluminum bonding wires,to the drain electrode of the second semiconductor circuit chip. A highcurrent intensity through the half-bridge circuit is then made possibleby using the fifth lead connection if, for example, a load is connectedto the node and the HSS semiconductor circuit chip is turned on.

In one embodiment, the circuit structure is partly constructed on acircuit carrier composed of ceramic and has a large-area contact pad ofa copper plate which is embedded into the ceramic material and which iscoated with a diffusion solder material. The semiconductor circuit chipsto be connected to a diffusion solder layer only have to be pressed ontothis large-area metal plate at diffusion solder temperature.

On the other hand, it is also possible for the metal plate composed ofcopper to remain uncoated and for only the large-area electrodes of thesemiconductor circuit chips to have a coating composed of diffusionsolder material. With this solution, the diffusion solder layer areascan be minimized. The circuit carrier composed of ceramic materialfurthermore has one advantage that, on the one hand, it has a higherthermal conductivity than a surrounding molding compound composed ofplastic and, on the other hand, this lead carrier composed of ceramic,for the diffusion solder process, can be heated to the elevatedtemperatures of up to 450° C. for the diffusion soldering without beingdamaged.

Furthermore, it is possible for the circuit structure to have amultilayered contact pad having a copper layer as base layer and anupper layer composed of diffusion solder material. In this case, whichin particular for the small-area contact pads, only the ceramic materialof the circuit carrier is provided with a copper layer, the embedding ofa metal plate being omitted.

The circuit structure can be enclosed by an encapsulant which embeds thelead connections, external contact areas of the lead connections on theunderside of the semiconductor switching module and internal contactareas at a level of the abovementioned circuit carrier remaining free ofencapsulant, in order to fit the connecting elements such as aluminumbonding wires, bonding tape connections and/or gold bonding wires in afurther process.

In an extended embodiment, a free wheeling diode is additionallyprovided on the circuit structure. Free wheeling diodes of this typeprotect the semiconductor circuit chips against overloads and arearranged between the source and drain of the semiconductor chips.

In one embodiment, the semiconductor circuit chips have verticalcharge-compensated MOSFETs as power switches. These verticalcharge-compensated MOSFETs have a minimized forward resistance and canswitch high currents at a low forward resistance. They can additionallybe equipped with an integrated gate driver circuit, whereby thereliability of the semiconductor switching module is increased. Finally,it is possible to provide as gate electrode a vertical trench gateelectrode in the semiconductor circuit chips, whereby a technologicalimprovement of the semiconductor switching module once again becomespossible. A semiconductor switching module of this type is used as abattery protection circuit or as a motor bridge circuit or as part of aDC/DC and/or AC/DC converter.

A method for producing a semiconductor switching module has thefollowing method. A first process involves producing a circuit structurecomposed of copper plates, which are embedded into a circuit carriercomposed of ceramic, for at least one large-area contact pad and asmall-area contact pad on the top side of the circuit carrier.Furthermore, lead connections are produced with external contact areasat the level of the underside of the circuit carrier and internalcontact areas at the level of the top side of the circuit carrier.

A circuit structure is thus provided on which the further components ofthe semiconductor switching module can then be applied with theirconnecting elements. For this purpose, firstly semiconductor circuitchips of the MOSFET type are produced. Afterward, the electrodes of thesemiconductor circuit chips and/or the contact pads, the externalcontact areas and the internal contact areas are coated with a diffusionsolder material. The circuit structure is then equipped with at leastone semiconductor circuit chip using flip-chip technology with diffusionsoldering of source electrode and gate electrode onto correspondingcontact pads of the circuit structure by virtue of a contact pressurebeing exerted on the semiconductor circuit chips at a diffusion soldertemperature. After the semiconductor circuit chips have been fixed onthe contact pads of the circuit carrier, connecting elements are fittedbetween electrodes of the semiconductor circuit chips or between contactpads of the circuit structure and the internal contact areas of the leadconnections.

Finally, the now functional semiconductor switching module can beincorporated into a module housing. The module housing may include anencapsulant which completely encloses the individual components apartfrom the external contact areas of the lead connections. However, amodule housing of this type may also have a metal enclosure which, inone embodiment, simultaneously serves as a cooling area.

In one exemplary implementation, before the diffusion soldering of theelectrodes of the semiconductor power chips on the contact pads of thecircuit carrier, diffusion solder layers composed of the diffusionsolder material are applied to the electrodes of the semiconductorcircuit chips, which layers have at least one of the materials AuSn,AgSn, CuSn and/or InAg and form, during diffusion soldering,intermetallic phases whose melting points are higher than a diffusionsoldering temperature. In this case, the diffusion soldering temperatureT_(D) at which the semiconductor circuit chips are applied by theirelectrodes to the contact pads of the circuit structure is between 180°C.≦T_(D)≦450° C.

For preparing the lead connections, a leadframe can be produced from ametal plate, a planar copper plate with a plurality of semiconductorswitching module positions. For the purpose of structuring the planarmetal plate, the latter can be stamped and/or subjected to wet or dryetching in order to work the lead connections there from. On the otherhand, it is also possible to produce a leadframe with a leadframestructure by using metal material electrodeposited on an auxiliarycarrier and to remove the auxiliary carrier again after thesemiconductor switching modules have been completed.

Bonding wire connections are introduced for the purpose of fittingconnecting elements between a small-area gate electrode of the top sideof a semiconductor circuit chip and provided internal contact areas oflead connections of the leadframe in the semiconductor switching modulepositions. On the other hand, bonding tapes or aluminum bonding wiresare used as connecting elements if high currents are to be transported,as for connections between large-area electrodes of the semiconductorcircuit chips and the provided internal contact areas of correspondinglead connections.

Since, in the case of this technique on a leadframe, a plurality ofsemiconductor switching modules arise in the semiconductor switchingmodule positions of the leadframe, the leadframe is subsequentlyseparated into individual semiconductor switching modules by using alaser separating technique or a stamping technique or a sawingtechnique. However, such separation can also be effected by using anetching method.

FIG. 1 illustrates a schematic cross section through a semiconductorswitching module 21 of one embodiment. The semiconductor switchingmodule 21 has semiconductor chips 22, wherein a first semiconductorcircuit chip 24 is arranged as LSS (low side switch) and a secondsemiconductor circuit chip 25 is arranged as HSS (high side switch) of ahalf-bridge circuit 23, which is illustrated in FIG. 3. A node K of thehalf-bridge circuit is formed by a copper plate 20 embedded in a circuitcarrier 19 composed of ceramic material, wherein, on a large-areacontact pad 12 of the copper plate 20, the drain electrode D₁ on therear side 15 of the first semiconductor circuit chip 24 is fixed byusing a diffusion solder layer 14 and the source electrode S₂ on the topside 16 of the second semiconductor circuit chip 25 arranged usingflip-chip technology is fixed by using a further diffusion layer 14.

Via the common copper plate 20, high currents can flow between the drainelectrode D₁ of the first semiconductor circuit chip 24 and the sourceelectrode S₂ of the second semiconductor circuit chip 25 without thesemiconductor switching module 21 heating up to an impermissible extent.There is furthermore applied on the circuit carrier 19 composed ofceramic a small-area contact pad 13 as copper layer 26, which isconnected to a small-area gate electrode G₂ of the second semiconductorcircuit chip 25 by using a diffusion layer 14. Alongside the copperplate 20 as node K of the half-bridge circuit, in the case of thissemiconductor switching module 21, at least five lead connections 7 areprovided, the lead connections 2 and 4 of which are illustrated in thiscross section. The lead connections 2 and 4 have external contact areas8 at the underside 10 of a common circuit structure 6, whichsimultaneously forms the underside 29 of the semiconductor switchingmodule 21, via which external contact areas the gate electrodes G₁ andG₂ of the first and the second semiconductor circuit chip 24 and 25,respectively, can be accessed.

For this purpose, a bonding wire 18 is fixed on the internal contactarea 9 of the second lead connection 2, which bonding wire ends on thegate electrode G₁ of the top side 16 of the first semiconductor circuitchip 24. Since only signal currents flow via the bonding wire 18, abonding wire having a thickness of a few micrometers can be used here.The same applies to the lead connection 4, via the external contact area8 of which access to the gate electrode G₂ of the second semiconductorcircuit chip 25 arranged using flip-chip technology is made possible.Here, too, the internal contact area 9 of the lead connection 4 isconnected to a contact pad 13 on the circuit carrier 19 by using abonding wire 18 having a thickness of a few micrometers, wherein thesmall-area contact pad 13 is simultaneously connected to the gateelectrode G₂ of the second semiconductor circuit chip 24 by using adiffusion solder layer 14.

The source electrode S₁ of the first semiconductor circuit chip 24 iselectrically connected, by using aluminum bonding wires 17, to theground potential GND via a further lead connection 7 (not illustrated).The drain electrode D₂ of the second semiconductor circuit chip 25 isalso electrically connected, by using aluminum bonding wires 17, to alead connection 7 (not shown) that is at a supply potential V_(BB). Thetop side 11 of the common circuit structure 6 and also the twosemiconductor circuit chips 24 and 25 and the connecting elements 30 areembedded into an encapsulant 28, which simultaneously forms the modulehousing 31.

FIG. 2 illustrates a schematic plan view of a circuit structure 6 for asemiconductor switching module 21 in accordance with FIG. 1. Arranged inthe center of the circuit structure 6 is a metal plate 20, which, withits top side, forms a large-area contact pad 12 of the circuit structure6. This copper plate 20 is embedded flush in a circuit carrier 19composed of ceramic material. Arranged alongside the large-area contactpad 12 is a small-area contact pad 13, which includes a copper coatingon the circuit carrier 19 composed of ceramic material.

The small-area contact pad 13 serves for receiving a gate electrode of asecond semiconductor circuit chip and for connection to a leadconnection 4 of the lead connections 7 that are arranged in two edgeregions of the circuit structure 6. Only the internal connection areas 9of the lead connections 7 can be seen in this plan view. The circuitcarrier 19 composed of ceramic and also the metallic lead connections 7are embedded into an encapsulant 28 that keeps the contact pads 12 and13 and the internal contact areas 9 and also the external contact areasof the lead connections 7 free of encapsulant.

FIG. 3 illustrates a schematic circuit diagram of a half-bridge circuit23 for an on-board electrical supply system. The semiconductor circuitchips LSS and HSS are arranged in series between the supply potentialV_(BB) and the ground potential GND and thus between the leadconnections 1 and 5. A node K is arranged between the two semiconductorcircuit chips 24 and 25, at which node the drain electrode D₁ of the LSSand the source electrode S₂ of the HSS are combined and can becontact-connected via the lead connection 3. The respective gateelectrodes G₁ and G₂ can be driven via the lead connections 2 and 4. Ahalf-bridge of this type is realized on a circuit structure 6 with FIG.4.

FIG. 4 illustrates a schematic plan view of an equipped circuit carrier19. The covering of the semiconductor switching module 21 and theencapsulant as illustrated in FIG. 1 have been omitted in order toillustrate the equipping of the circuit carrier 19. A large-area contactpad 12 and a small-area contact pad 13 are situated on the circuitcarrier 19 composed of ceramic, the circuit carrier being surrounded byan encapsulant 28. While the large-area contact pad 12 belongs to acopper plate 20 embedded into the circuit carrier 19 composed of ceramicmaterial, the small-area contact pad 13 is formed by a copper layer 26.The semiconductor chips 22 are arranged on the metal plate 20, whereinthe first semiconductor circuit chip 24 is fixed by its drain electrodeon the metal plate 20 and the second semiconductor circuit chip 25 isarranged by its source electrode on the common large-area contact pad 13of a copper plate 20.

Consequently, the copper plate 20 forms the node K, which is illustratedfor a half-bridge in FIG. 3. The node K is accessible via aluminum wires17 and the third lead connection 3 in the encapsulant. A groundpotential GND can be applied to the source electrode S₁ of the firstsemiconductor circuit chip 24 via the lead connection 1. Finally, thedrain electrode D₂ of the second semiconductor circuit chip can beaccessed via a fifth lead connection 5. In this case, a sixth leadconnection 7 is not connected up, especially as the half-bridge asillustrated in FIG. 3 manages with five lead connections 1 to 5.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat a variety of alternate and/or equivalent implementations may besubstituted for the specific embodiments illustrated and describedwithout departing from the scope of the present invention. Thisapplication is intended to cover any adaptations or variations of thespecific embodiments discussed herein. Therefore, it is intended thatthis invention be limited only by the claims and the equivalentsthereof.

1. A semiconductor module comprising: a ceramic circuit structure: atleast one half-bridge circuit comprising a first semiconductor circuitchip as a low side switch and a second semiconductor circuit chip as ahigh side switch the common circuit structure; contact pads on a topside of the circuit structure: lead connections with external contactareas on an underside of the circuit structure; internal contact areason the top side of the circuit structure; the second semiconductorcircuit chip arranged on contact pads of the circuit structure usingflip-chip technology, wherein the circuit structure has a large-areacontact pad which receives and is directly connected to a drainelectrode of the first semiconductor circuit chip and to a sourceelectrode of the second semiconductor circuit chip, and a small-areacontact pad which is electrically connected to a gate electrode of thesecond semiconductor circuit chip.
 2. The module of claim 1, comprisingwherein the first and the second semiconductor circuit chip are powersemiconductor components of a MOSFET type which have, on their rearsides, large-area surface-mountable drain electrodes and, on their topsides, surface-mountable electrodes comprising a large-area sourceelectrode and a small-area gate electrode.
 3. The module of claim 1,wherein the first semiconductor circuit chip is surface-mounted by itslarge-area drain electrode on its rear side, by a diffusion solderlayer, on a large-area contact pad of the circuit structure using directcopper bonding, wherein the contact pad is simultaneously connected tothe large-area source electrode of the top side of the secondsemiconductor circuit chip mounted using flip-chip technology in such away that the large-area contact pad forms a node of the half-bridgecircuit.
 4. The module of claim 1, comprising wherein diffusion solderlayers have at least one of the materials AuSn, AgSn, CuSn and/or InAgas diffusion solder material.
 5. The module of claim 1, comprisingwherein the semiconductor module has at least five lead connections. 6.The module of claim 1, comprising wherein a first lead connection isconnected to ground potential by its external contact area and isconnected by its internal contact area, by using a bonding tapeconnection or by using aluminum bonding wires, to the source electrodeof the first semiconductor circuit chip.
 7. The module of claim 1,comprising wherein a second lead connection enables, via its externalcontact area an access to a gate electrode of the first semiconductorcircuit chip, wherein the internal contact area of the second leadconnection is connected to the gate electrode of the first semiconductorcircuit chip by using a bonding wire.
 8. The module of claim 1,comprising wherein a third lead connection enables, by its externalcontact area an access to a node of the semiconductor switching module,wherein the internal contact area of the third lead connection isconnected to a common contact pad of the circuit structure by using abonding tape connection or by using aluminum bonding wires.
 9. Themodule of claim 1, comprising wherein a fourth lead connection enables,via its external contact area an access to a gate electrode of thesecond semiconductor circuit chip, wherein the internal contact area ofthe fourth lead connection is connected to a small-area contact pad ofthe circuit structure by using a bonding wire, and wherein the gateelectrode of the second semiconductor circuit chip is fixed on thesmall-area contact pad by using a diffusion solder layer using flip-chiptechnology.
 10. The module of claim 1, comprising wherein a fifth leadconnection is connected to a supply potential by its external contactarea and is connected by its internal contact area, by using bondingtapes or by using aluminum bonding wires, to the drain electrode of thesecond semiconductor circuit chip.
 11. The module of claim 1, comprisingwherein the circuit structure is constructed on a circuit carriercomposed of ceramic and has a large-area contact pad of a copper platewhich is embedded into the ceramic material and which is coated with adiffusion solder material.
 12. The module of claim 1, comprising whereinthe circuit structure has a multilayered contact pad having a copperlayer as base layer and an upper layer composed of diffusion soldermaterial.
 13. The module of claim 1, comprising wherein the circuitcarrier is enclosed by an encapsulant and embeds the leads whereinexternal contact areas of the lead connections on the underside of thesemiconductor switching module and internal contact areas at a level ofa circuit carrier remain free of encapsulant.
 14. The module of claim 1,comprising wherein a free wheeling diode is additionally arranged on thecircuit structure.
 15. The module of claim 1, comprising wherein atleast one of the semiconductor circuit chips mounted on contact padsusing flip-chip technology of the circuit structure is electrically andcohesively connected to the contact pads by using diffusion solderlayers.
 16. The module of claim 1, comprising wherein the semiconductorcircuit chips have vertical charge-compensated MOSFETs, wherein at leastone semiconductor circuit chip has an integrated gate driver circuit inaddition to the MOSFET.
 17. The module of claim 1, wherein the gateelectrode is a vertical trench gate electrode.
 18. The use of the moduleof claim 1 as a battery protection circuit.
 19. A semiconductor modulecomprising: a circuit structure; at least one half-bridge circuitcomprising a first semiconductor circuit chip as a low side switch and asecond semiconductor circuit chip as a high side switch on the commoncircuit structure: contact pads on a top side of the circuit structure;lead connections with external contact areas on an underside of thecircuit structure; internal contact areas on the top side of the circuitstructure; the second semiconductor circuit chip arranged on contactpads of the circuit structure using flip-chip technology, the circuitstructure including a large-area contact pad directly connected to adrain electrode of the first semiconductor chip and to a sourceelectrode of the second semiconductor chip; and an on-board electricalsupply system.